In modern motor vehicles, it is increasingly common for switching and control elements to be pneumatically actuated, these generally being connected to a vacuum reservoir for this purpose. Such vacuum reservoirs are normally connected to the air intake system of the internal combustion engine, because a vacuum prevails there at certain operating points. Modern direct-injection Otto-cycle internal combustion engines are commonly operated without throttling, such that the provision of a vacuum for the vacuum reservoir is generally assisted by means of a vacuum pump.